1996-1997 New England Apple Pest Management Guide


 FRUIT FINISH AND PHYTOTOXICITY

Certain pesticides, formulations or pesticide combinations can produce or increase fruit russeting under certain conditions. Risk of russeting is increased by overdosage, and by application when the temperature is over 80oF or during poor drying conditions.

Low temperatures (frost) and genetic or physiological factors also contribute to poor fruit finish. Golden Delicious, Red Delicious and even McIntosh are sensitive to certain pesticides.

Also check Table 19 - Spray Mixture Incompatibility before tankmixing.

PESTICIDE

Benlate (benomyl) Do not tank-mix with copper-containing materials or with highly alkaline pesticides, such as Bordeaux mixture or lime sulfur. Within 40 days of petal fall, Benlate can exacerbate 'scarf skin' on Delicious.

captan Do not use within 10 days before or after an oil application, do not combine with EC formulations of some other pesticides. Has caused spotting, yellowing and dropping of leaves when used before 3 weeks after petal fall on Delicious, Spartan and Baldwin. Injury is enhanced when combined with sulfur. Has given good fruit finish.

coppers (Kocide, COCS, Caution is advised for use after silver tip. Sprays containing copper may

Basicop, Blue Shield, cause damage to young foliage or cause fruit russeting, particularly under

Tri-Basic etc.) slow drying conditions. Risk of fruit russeting increases by half-inch green. Do not allow Kocide solution pH to fall below 6.5.

diazinon Has caused russeting on Golden Delicious, R.I. Greening and Baldwin. Do not combine with copper. May cause poor finish or russeting if used under poor drying conditions or before second cover on sensitive cultivars.

Carbamate (ferbam) May cause lenticel enlargement on some cultivars. May cause severe russeting on Golden Delicious and other cultivars that russet easily, especially if it is applied in the pink through first cover periods. Late-season use can leave visible residue on fruit and foliage.

insecticidal soap May cause fruit russeting under poor drying conditions.

(Safer's, M-Pede)

Kelthane (dicofol) Has caused necrotic fruit spotting when combined with dodine, Kocide or highly alkaline materials. Combination of Kelthane 50WP and summer oil has caused fruit spotting and enlarged lenticels when applied during poor drying conditions. Liquid formulation may cause fruit russeting under slow drying conditions.

Lannate (methomyl) Do not use on Early McIntosh or Wealthy.

Morestan Do not tank-mix with oil, sulfur or spreader-stickers. Under slow drying

(oxythioquinox) conditions, injury may occur to new and/or tender growth. Combination with EC formulations may cause phytotoxicity. Wait at least 10 days or one growth stage from an oil spray. Do not use after first bloom.

PESTICIDE

oil (horticultural) Oil injury generally appears as swollen and cracked lenticels and/or bark blistering. It is caused mainly by double deposit (allowing one side to dry before the other side is sprayed), by concentrate sprays or by application when low temperatures (below 38oF and particularly below freezing) occur within 24 hours, especially on Delicious.

Oil may cause phytotoxicity if used within 10 days before or after captan or Morestan. The safe interval is much longer for sulfur. Oil has questionable or limited compatibility with many other pesticides, including Guthion, Sevin and Vydate. Check labels and Table 19 before tank-mixing.

Yellowing leaves are the first sign of summer oil phytotoxicity and indicate that the rate of oil should be reduced for any subsequent applications. There is a high potential for phytotoxicity and fruit finish damage with summer oil use. Cultivar, adequate moisture, and spray drying conditions should be considered before using summer oil to minimize detrimental effects on fruit finish.

Sevin (carbaryl) Foliar injury may result when used at petal fall and first cover on McIntosh and Cortland. Causes thinning if used within 30 days after full bloom. Questionable compatibility with oil.

sulfur Has russeted fruit when sprayed postbloom at above 80oF. May cause leaf spotting on Delicious and some other cultivars when combined with captan. Check label for restrictions on use around an oil application; certain labels prohibit the use of sulfur within 30 days of an oil application.

Syllit (dodine) At dosage of more than 1/2 lb./100 gals. dilute, dodine may cause injury if applied at freezing or near-freezing temperature, particularly when accompanied by slow drying conditions. May russet Golden Delicious. Do not combine with Kelthane in late cover sprays. In combination with sulfur, can cause leaf spotting on Delicious. Has caused necrotic spotting of McIntosh and Cortland fruit. Syllit 65W plus oil combinations are not compatible with wettable powder formulations of carbaryl, ferbam or sulfur.

Topsin-M Do not tank-mix with copper-containing materials or with highly alkaline (thiophanate-methyl) pesticides, such as Bordeaux mixture or lime sulfur. Within 40 days of petal fall, Topsin-M may exacerbate 'scarf skin' on Delicious.

CHECK PESTICIDE LABEL CAREFULLY FOR COMPATIBILITY BEFORE USING

SPRAY ADJUVANTS (WETTING AGENTS, SPREADERS, STICKERS, ETC.)

On to Spray Mixture Incompatibility

 

 


1996-1997 New England Apple Pest Management Guide